The present invention is directed to the field of equipment and accessories for processing semiconductor wafers. More particularly, it is directed to a device which is used to facilitate demounting a semiconductor wafer which has been adhesively mounted to a carrier disc used for support during a manufacturing operation.
During semiconductor manufacture, a semiconductor wafer is placed on a carrier which provides mechanical support to the wafer, as the wafer is sent through various processing steps. An adhesive may be used to bond the wafer to the carrier to provide support while preventing slippage. Once the processing steps are over, a mechanical device may be used to debond and/or demount the wafer from the carrier. The prior art includes a number of devices that can be used to lift a wafer from a surface.
U.S. Pat. No. 5,479,108 to Cheng discloses a wand member attached to an end of a mechanical wafer pick. The wafer pick travels in a longitudinal direction in a plane substantially parallel to the surface of a chuck on which a wafer rests. The wand member slides under a wafer and rises to lift the wafer off of the surface of a chuck.
U.S. Pat. Nos. 4,984,954 and 4,867,631 to Warenback et al. disclose a spatula for wafer transport. The spatula contains a single major recess for receiving a wafer. Adjacent one edge of the recess is a shoulder for locating the wafer in the sequence of operations for loading the spatula. As a result of the sequence, the center of the wafer is held at a predetermined, known location.
U.S. Pat. No. 4,971,512 to Lee et al. discloses a transport device for handling wafers of different diameters. A robotic arm is equipped with a fork-shaped wafer support board and an arm slide movable relative to the robotic arm. The fork-shaped end of the support board is provided with fixed pins on one side to support wafers and on another side with plate springs carrying pins which can be depressed by the weight of a wafer to accommodate larger size wafers. The device permits wafers of different diameters accurately and safely to be transferred from its center to a predetermined station without the need for changing the wafer support board or correction of the robotic arm.
U.S. Pat. No. 4,875,824 to Moe et al discloses a transfer mechanism to pick up a wafer from one location, lift it, transfer it laterally, lower it and later deposit it another location. A horizontal feedscrew mounted in a stationary base controls horizontal reciprocation of a transverse housing. A vertical feedscrew mounted in the transverse housing controls vertical reciprocation of a second housing. Supported by the second housing are one or more lifts. Each lift has guide rods fixed relative to the second housing and a stop on its lower end. Parallel and adjacent the guide rods is a reciprocating rod carrying a gripper on its lower end. At the end of the vertical movement of the second housing the reciprocating rod moves the gripper away from the stop so that a wafer may rest on the guide rods. As the second housing moves up, the gripper clamps the wafer against the stop. Motors drive the feedscrews to lift the wafer, move it transversely and lower it. As it reaches the end of its lowering movement, the wafer is unclamped.
U.S. Pat. No. 4,619,573 to Rathmann et al. discloses a rail guided, magnetically driven shuttle plate. Baffles serve to isolate the particle producing portions of the mechanism from the wafers. The major drive components are located inside the rails and outside the vacuum containment system. A pin lift apparatus located on the reactor chucks serves to remove and replace wafers on the shuttle plate.
U.S. Pat. No. 4,496,180 to Hillman et al. discloses a vacuum operated apparatus is for releasably grasping and transporting a thin solid object or article (e.g. silicon semiconductor wafer). The apparatus has two fixed rigid arms joined together at their rear end to define a gap therebetween having an open end and a closed end wherein the upper arm directs the thin solid object into the gap and toward the lower arm having a port communicating with the gap and an enclosed passage way connected to a vacuum source. The device is provided with a plate fixed to the bottom of the lower arm. Silicon semiconductor wafers may be grasped and transported with the apparatus and more especially silicon semiconductor wafers can be deposited onto and removed from the surface of a barrel type susceptor of an epitaxial reactor with enhanced ease and reduced danger of scratching and breaking the wafer.
The wafer demount fixture of the present invention comprises a hand-held spatula specially configured to remove a brittle wafer from a carrier plate. The spatula is provided with at least one support guide slidably mounted therreon, the support guide permitting longitudinal movement of the spatula, when the support guide is fixed to a mounting surface. As the spatula moves in a longitudinal direction, a front edge of a wafer support surface of the spatula eases under a wafer, thereby lifting the wafer from a supporting carrier in a manner which minimizes chances of breaking the wafer. A handle member of the spatula is provided with a grip having an abutment surface configured to abut a base plate on which the spatula is mounted, thereby preventing the spatula from being moved too far in the direction of the wafer.